Fluorine profiles in human enamel after in vitro treatment with dentifrices of different compositions and acidities.

Fluorine uptake has been measured in human enamel after in vitro treatment with slurries of dentifrices of different compositions and acidities. Secondary ion mass spectrometry (SIMS) was used to determine the quantitative in-depth distribution profiles of fluorine. Five dentifrices were examined: ACTA (pH 5.5) with 250, 1000 and 1500 ppm F as NaF; Colgate (pH 7) with 1000 ppm F as MFP and 400 ppm F as NaF; and Pepsodent (pH 7) with 1000 ppm F as MFP. The results establish that acidulated dentifrice with low F concentration gives about the same fluorine uptake in near-surface enamel as do pH 7 dentifrices with higher F contents. In addition, at depths greater than ca 3 microns, the low F acid dentifrice in fact introduces considerably higher levels of fluorine, and yields at least three times deeper penetration, than do the non-acidulated toothpastes. The study illustrates the advantages of enhanced fluorine uptake, and thereby improved cariostatic effect, by using acidulated dentifrices even at relatively low fluoride concentration.